REX (ELECTROLUX) IR023S YEAR 1990.

This REX (ELECTROLUX)  IR023S  was superficially scrapped by the owner only for a defective Compressor starting  relay, an easy & cheap FIX. (that idiot surently bought a modern cellular look refrigerator toy claimed as AAAAAAAAAAA+++++++++++ shithole wich won't last more than 3 / 5 years !)

Obviously it was dirty and dusty, so I've cleaned and restored to fully functional working order.

The REX (ELECTROLUX)  IR023S Refrigerator is really a beast it comes Up to evaporation In the Freezer compartment in 12 sec after compressor start  even waiting a 24Hr of a complete stop and the Freezer compartment it's cooled in a time inferior  as 18 mins.

This is first  REX  IR023S  model series fabricated under ELECTROLUX control because the model was originally earlier designed and fabricated in ZANUSSI Factory but shapes and construction art was different.
Therefore all metal sheet shapes are differently fabricated compared to older models, others particulars too.


It's super silent.

All parts are original and furthermore this here was good used and cared.........then throwed away for a cheap fix........

Compressor VOE (VERDICHTER VOE  V1040N R-12 110WATT.

REX (ELECTROLUX)  IR023S  REFRIGERATING APPLIANCE WITH SINGLE THERMOSTATIC TEMPERATURE CONTROL DEVICE:

The present invention relates to a refrigerating appliance comprising a refrigerating circuit provided with a thermostatic temperature control arrangement.
Particularly, but not exclusively, the present invention relates to a multi-temperature refrigerating appliance provided with a single thermostatic temperature control device.
Two-temperature refrigerating appliances are well known, having two main compartments which are kept at different temperatures and provided with independent access doors. Usually, one of the compartments is maintained at an average temperature of about + 5 DEG C for preserving fresh goods, whereas the other compartment is maintained at an average temperature of about - 18 DEG C for freezing purposes.
Preferably, such refrigerating appliances utilize one single-compressor refrigerating circuit in which two evaporators associated with relevant storage and freezer compartments are connected in series. An embodiment of this kind is for instance disclosed in EP-A-0 298 349.
The temperature in the refrigerating appliance, determined by alternate operative and inoperative phases of the compressor, is usually controlled by means of a single thermostatic control device which is capable of sensing, directly or indirectly, the temperature of the evaporator associated with the storage compartment.
More particularly, the compressor is actuated when the temperature of the storage compartment evaporator exceeds a given maximum value and is deenergized, in order to perform a corresponding defrost phase of the storage compartment evaporator, when the above temperature falls below a predetermined minimum value. The temperature inside the compartments depends on the ON/OFF ratio in the operating cycle of the compressor, as well as on the general dimensions of the refrigerating appliance, its loading conditions and the ambient temperature.
It is known, in this condition, that when the ambient temperature is particularly low the thermostatic control device makes the compressor run with correspondingly reduced operative phases with respect to the inoperative phases, in order to maintain the predetermined average temperature of approx. + 5 DEG C in the storage compartment. Under these operating conditions, therefore, the freezer compartment is likely to be cooled insufficiently by the associated evaporator, with a consequent deterioration of the goods contained in the freezer compartment itself. Anyway, the long inoperative phases of the compressor in case of particularly low ambient temperature cause undesirably wide temperature fluctuations to occur in both compartments, and this is in contrast with a desirable correct operation.
In order to overcome the above drawbacks it is common practice to provide a so-called "balancing" heating element (consisting of a heating resistance, for example) in the storage compartment, the heating element being controlled by the thermostatic control device to be actuated in place of the compressor during the inoperative phases of the compressor itself.
The amount of heat generated by the balancing resistance during the defrost phases of the storage compartment evaporator artificially compensated for the low ambient temperature, in this way promoting a better ratio between the ON and OFF phases of the compressor, thus enabling the freezer compartment to be refrigerated correctly and causing narrower temperature fluctuations to occur in both compartments.


REX (ELECTROLUX)  IR023S  Temperature control for a cycle defrost refrigerator incorporating a roll-bonded evaporator :

 A temperature control system for a refrigerator including a roll-bonded evaporator in the fresh food compartment in which is formed a non-refrigerant carrying passageway extending the full width of the evaporator. A temperature control located in the compartment includes a temperature sensitive capillary tube portion extending substantially the full length of the passageway so as to be subjected to the limited environment of the passageway and accordingly responsive to the true temperature of the evaporator.

 1. A cycle defrost household refrigerator including a cabinet having an upper lower temperature food compartment and a lower relatively high temperature food compartment, evaporator means for refrigerating said compartments comprising:
a first evaporator located in said low temperature compartment and a second evaporator arranged substantially vertically in said relatively high temperature compartment and connected to said first evaporator in series refrigerant flow relationship;
means for supplying liquid refrigerant to said liquid carrying conduits in said first and second sections in series and for withdrawing evaporated refrigerant therefrom;
a temperature control means in said high temperature food compartment including a temperature sensitive capillary tube portion having a length corresponding substantially to the width of said second evaporator;
said temperature control being operable by the coldest temperature sensed along the length of said capillary for causing said compressor to cycle off to cause defrosting of said section of said evaporator;
a passageway positioned in heat exchange relationship to said second evaporator extending substantially the entire width between the vertical sides thereof;
said passageway having a cross-sectional dimension for allowing insertion of said capillary tube portion to a position substantially the full length of said passageway and for insuring thermal relationship between said capillary tube portion and said passageway so that said capillary tube portion is subjected to the limited environment of said passageway and the temperature of said second section.


2. The household refrigerator recited in claim 1 wherein said passageway is arranged below the liquid carrying conduits.

3. The household refrigerator recited in claim 2 wherein said passageway is formed to include a central apex from which said passageway extends downwardly and outwardly.

4. The household refrigerator recited in claim 3 wherein there is further provided a drain means located below said passageway for receiving defrost water from said second section of said evaporator.

5. A cycle defrost household refrigerator including a cabinet having an upper low temperature food compartment and a lower relatively high temperature food compartment, evaporator means for refrigerating said compartments comprising: a one piece evaporator formed of a pair of sheets roll-forged together to include liquid carrying conduits between said sheets, said evaporator having a first section located in said low temperature compartment formed in a U-shape to include a back wall portion having substantially horizontally extending upper and lower wall portions and having a second section arranged substantially vertically in said relatively high temperature compartment and connected to said first section by means of a relatively narrow neck portion;
means for supplying liquid refrigerant to said liquid carrying conduits in said first and second sections in series and for withdrawing evaporated refrigerant therefrom;
a temperature control means in said high temperature food compartment including a temperature sensitive capillary tube portion having a length corresponding substantially to the width of said second evaporator.
said temperature control being operable by the coldest temperature sensed along the length of said capillary for causing said compressor to cycle off to cause defrosting of said section of said evaporator.
a passageway formed between the pair of sheets of said second section extending substantially the entire width between the vertical sides thereof;
said passageway having a cross-sectional dimension for allowing insertion of said capillary tube portion to a position substantially the full length of said passageway and insuring thermal relationship between said capillary tube portion and said passageway so that said capillary tube portion is subjected to the limited environment of said passageway and the temperature of said second section.


6. The household refrigerator recited in claim 5 wherein said passageway is arranged below the liquid carrying conduits.

7. The household refrigerator recited in claim 6 wherein said passageway is formed to include a central apex from which said passageway extends downwardly and outwardly.

8. The household refrigerator recited in claim 7 wherein there is further provided a drain means located below said passageway for receiving defrost water from said second section of said evaporator.

Description:

BACKGROUND OF THE INVENTION
The present invention relates to cycle defrost refrigerator wherein defrost of the fresh food compartment evaporator is accomplished during the compressor OFF cycle primarily by convection of the relatively warm above freezing fresh food compartment air and through the heat leakage entering the fresh food compartment and more particularly to a control system for a cycle defrost refrigerator incorporating a roll-bond evaporator.
Generally in a cycle defrost refrigerator the temperature of the fresh food compartment is maintained by sensing the true temperature of the evaporator. This requires that the entire length of the thermostat control capillary tube be maintained in heat exchange relationship with the evaporator. Traditionally many cycle defrost refrigerators suffer from the inability of the control capillary to sense the true fresh food evaporator conditions under critical usage conditions. This often results from the inconsistencies of arranging the control capillary tube relative to the fresh food evaporator so that it will sense accurate evaporator conditions. These control errors often result in residual icing problems, premature compressor trip-offs, and a wide dispersal of operating response characteristics. One common manner of securing the control capillary to the evaporator to insure that the full length of the capillary tube is in contact with the evaporator has been to employ a plurality of clamps spaced along the entire length of the capillary tube. This method requires the use of external parts and labor to secure them to the evaporator and falls short of solving the problem since the relatively small diameter capillary tube realistically cannot conform to the surface of the evaporator.

SUMMARY OF THE INVENTION
An object of the present invention is to provide a passageway which extends across the full width of the roll-bonded plate evaporator and whose cross-sectional area assures introduction of the capillary tube to a position occupying the full length of the passageway so that it is in contact with the walls of the passageway.
By the present invention there is provided in a houshold refrigerator having an upper low temperature food compartment and a lower relatively high temperature food compartment including a one-piece evaporator for refrigerating the compartments. The one piece evaporator is formed of a pair of sheets roll-forged together to include liquid carrying conduits between the sheets. The evaporator has a first section located in the low temperature compartment and a second section arranged substantially vertically in the relatively high temperature compartment and connected to the first section by means of a relatively narrow neck portion. A hermetic compressor supplies liquid refrigerant to the liquid carrying conduits in the evaporator sections in series and for withdrawing evaporated refrigerant therefrom. Located in the high temperature compartment is a temperature control means including a temperature sensitive capillary tube portion. A passageway is formed between the pair of sheets of the second section of the evaporator. The passageway is located below the liquid carrying conduits and extends between the vertical edges of the second section. The passageway has a cross-sectional area which is dimensioned to allow easy insertion of the capillary tube to a position where it occupies substantially the full length of the passageway while at the same time insuring accurate thermal response between the temperature sensitive capillary tube portion and passageway walls so that the capillary tube portion is subjected to the limited environment of the passageway and accordingly the true temperature of the second section of the evaporator.

BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a sectional view of a two compartment refrigerator incorporating the present invention;
FIG. 2 is a partial front elevational view with the cabinet door removed showing the lower compartment evaporator incorporating the present invention;
FIG. 3 is an enlarged cross-sectional view along line 3--3 of FIG. 2 showing the arrangement of the control tube in conjunction with the illustrated embodiment of the present invention; and
FIG. 4 is a diagramatic showing of the one-piece two-section evaporator incorporated in the embodiment of the present invention.

BRIEF DESCRIPTION OF THE INVENTION
Referring now to the drawing wherein a preferred embodiment of the invention has been shown, reference numeral 10 generally designates a conventional insulated refrigerator cabinet having a below freezing frozen food compartment 12 disposed in the upper part of the cabinet, an above freezing main food storage compartment 14 disposed below the freezer compartment 12, and a machinery compartment 16 arranged in the bottom portion of the cabinet. The frozen food compartment 12 is adapted to be maintained at a temperature low enough to properly preserve frozen food for long periods of time. Thus, the temperature therein is preferably maintained somewhere between -10° F. and 10° F. The main food storage compartment 14 is preferably maintained at temperatures above freezing but low enough to properly refrigerate perishable unfrozen foods. It has been found that temperatures in the range of 37° to 40 20 F. are most satisfactory for this purpose.

The compartments 12 and 14 are refrigerated by a one-piece roll-forged evaporator including evaporators sections 20 and 22 respectively which are connected in series flow in the refrigerant circuit. The refrigerating system used for maintaining the compartments 12 and 14 within the desired temperature ranges mentioned above employs a conventional motor compressor unit 18 which is adapted to be mounted in the machinery compartment 16 and which discharges compressed refrigerant into the condenser 24 positioned across the outside back wall of the refrigerator. Condensed liquid refrigerant from the condenser 24 then flow thru a conventional capillary tube (not shown) to the evaporator section 20 located in the freezer compartment and then to the series connected evaporator section 22 located in the food storage compartment 14.

The evaporators sections 20 and 22 are fabricated from two superimposed planar sheets made in one piece by a roll-forging operation. While the present invention does not reside in a roll-forging method as such, a brief general description of this method is included in order to facilitate a complete understanding of all aspects of the invention. The pair of sheets are superimposed upon one another with a pattern of stop-weld material coated on the one sheet. The stop-weld material provided between the sheets prevents the sheets from adhering to one another throughout the coated area. Following the roll-forging operation fluid under pressure is supplied between the sheets so as to dilate the sheets for the purpose of forming refrigerant passages corresponding to the pattern of the stop-weld material. The stop-weld material is so applied that the internal refrigerant passages extend throughout the major portion of the plate and in effect form two spaced evaporator sections connected in series refrigerant flow relationship. A slot 26 is cut in the composite plate after the roll-forging operation as shown in FIG. 4 so as to separate the evaporator section 20 from evaporator section 22 except at the narrow neck 28.

This narrow neck 28 includes a refrigerant passages 30 (FIGS. 2 & 4), which connects the evaporator section 20 in series with the evaporator section 22. In installing the evaporator sections 20 and 22 in the cabinet the evaporator section 22 may be arranged as shown in FIG. 2 with its vertical side edges 32 adjacent to side walls 34 of the food storage compartment cabinet and substantially parallel to the rear wall of compartment 14 as shown in FIG. 1. The evaporator section 20 as best shown in FIGS. 1 and 4 is folded into a U-shape configuration including a back wall 36 and horizontally extending top and bottom walls 38. It should be noted that other configurations of the freezer compartment evaporator may be used in conjunction with the present invention.
The temperature of the fresh food compartment 14 is regulated by a thermostatically operated temperature control 40 mounted on one side wall 34 in the compartment 14. The control 40 includes a manually adjustable control knob 41 used to select the fresh food compartment temperature and a control capillary tube 42 arranged as will be explained fully to be in contact with the lower portion of the evaporator section 22. The control 40 is used for starting and stopping the motor compressor unit 18 in response to the selected refrigeration requirements. The control 40 is of the type which is adapted to close the circuit to the motor compressor unit 18 when the temperature of the coldest portion of the control capillary 42 is a few degrees above the melting temperature of the frost which may form on the evaporator section 22 during the "ON" cycle of the compressor and is adapted to open the circuit to the compressor when the temperature of the coldest portion of the control capillary 42 approaches the selected evaporator OFF temperature. The relative sizes of the evaporators 20 and 22 and the arrangement of the passages therein are such to provide for automatic defrosting of the evaporator section 22 during the OFF cycle without defrosting the evaporator section 20. It is important to note that the control capillary 42 responds to evaporator temperatures rather than the temperature of the air in the food compartment as it has been found that the temperature of the air in the food storage compartment may be maintained substantially between 37° and 40° F. at all times even though the temperature of the evaporator 22 sensed by the bulb 42 fluctuates over a wide range such as -6° F. to 37° F. The temperature values given herein are primarily for purposes of illustration and may be varied to suit different requirements.
In order for the capillary tube 42 to respond to true evaporator temperature rather than air temperature and to obtain accurate temperature control it must control from the coldest point. In conventional practice this can only be accomplished if the capillary tube is securely and accurately positioned to be in direct contact with the evaporator surface over its full intended sensing contact area or length. To obtain uniform temperature calibrations for a multitude of cabinets of the same type, it is necessary that the same predetermined length of control bulb be arranged in heat exchange relationship with the evaporator wall in each cabinet and that this entire length be in heat relationship with the evaporator.
By the present invention the capillary tube 42 is positioned so as to respond to true evaporator conditions. To this end an open non-refrigerant passageway 50 is formed in the evaporator section 22. The passageway 50 as seen in FIG. 2 is positioned below the lowermost refrigerant pass 52 and the lower edge 54 of the evaporator 22. The passageway 50 extends across the full width of the evaporator and diverges downwardly and outwardly from a central apex 56. The capillary tube 42 is inserted the full length of the passageway 50 as shown by broken lines in FIG. 2 so as to be exposed to temperatures across the full width of the evaporator. For example, the temperature in the inlet area of refrigerant pass 52 might be different than that in outlet area of pass 52.

The length and cross-sectional area of the passageway 50 relative to the diameter and length of capillary tube 42 is such that the capillary tube 42 may be easily inserted therein while at the same time insuring that a thermal relationship is maintained between the capillary and evaporator. The capillary 42 is so positioned in the passageway 50 that it sees only the limited environment generated by the highly conductive walls of the passageway. In the control employed in carrying out the present invention the capillary controls from the coldest point along its length. The arrangement of the capillary and passageway extending across the evaporator insures that Off cycle will be initiated from coldest point along the width of the evaporator which is below freezing and an ON cycle which is initiated from the coldest part of the evaporator which is above the freezing temperature. The passageway 50 as stated above in effect creates an environment in which the capillary tube 40 can sense the true temperature of the evaporator.
By the present arrangement a constant temperature difference between the control capillary and the evaporator is generated which insures a consistent refrigeration cycle initiation and termination with respect to true evaporator conditions such as overall average temperature and frost conditions.
The capillary tube due to its location below the lowest refrigerant carrying pass senses the descending defrost water which impinges on the outer surface of the passageway. The above freezing temperature of the defrost water contacting the passageway 50 influences the temperature of the evaporator and accordingly the temperature sensed by the capillary tube 42. Defrost water impinging on the passageway 50 tends to flow downwardly toward the outer edges 32 and into trough 58 where it flows into a drain tube 60 to be disposed of by evaporation in the machine compartment 16 in any suitable manner (not shown).
While in the embodiment shown a single or one-piece evaporator is shown it should be noted that evaporator sections 20 and 22 may be separately formed and connected by appropriate refrigerant tubing.
Further, the passageway 50 may be formed by brazing or adhesively bonding a tube member to the plate evaporator. A tube so bonded to the evaporator would create the same environment for the capillary tube as formed passageway 50 does in that the capillary would still be in a position to sense true evaporator temperature.
It should be apparent to those skilled in the art that the embodiment described heretofore is considered to be the presently preferred form of this invention. In accordance with the Patent Statues, changes may be made in the disclosed apparatus and the manner in which it is used without actually departing from the true spirit and scope of this invention.

REX (ZANUSSI-ELECTROLUX)  IR023S  Method for making an improved evaporator. 

 A method for making an evaporator of the roll-bond type comprises a first step of inserting a return pipe (1) into a passage (3) formed between the two bonded sheets of the roll-bond evaporator (4), a second step of compressing said passage (3) about the terminal portion (8) of said return pipe so as to form a narrow and substantially annular space (12) between said roll-bond passage (3) and a length of said return pipe (1) inserted into said passage, and a subsequent third step consisting of the injection of a semi-fluid substance having sealing and adhesive properties into a further passage (9) obtained by suitably forming the two roll-bonded sheets and having one of its ends provided with a port (11) opening into said space (12), so that and until said substance progressively fills all or part of its volume.

1. A method for making an evaporator of the roll bond type, particularly for use in domestic refrigerating appliances, with a frist step comprising the insertion of a return pipe into a retrun passage formed between the two bonded sheet layers of the roll bond evaporator, a second step comprising the compression of said return passage about an end portion of said return pipe so as to form a narrow substantially annular space, preferably of a length of at least 20 mm, between the inner wall of said return passage and the outer face of said return pipe inserted therein, characterized by the provision of a third step comprising the injection of a semi-fluid substance having sealing and adhesive properties into a further passage (9) obtained by suitably shaping the two sheet layers of the roll bond structure, said further passage (9) having at one of its ends a port (11) opening into said space (12), so that and until said substance progressively fills all or part of the volume of said space.

2. A method according to claim 1, characterized in that said port (11) opens into said space (12) substantially adjacent the bottom thereof.

3. A method according to claim 2, characterized in that said sealing substance is of the anaerobic polymerization type.

4. A method according to claim 3, characterized in that subsequent to the filling of said space (12), the corresponding area of the roll bond structure is subjected to a heat treatment, preferably by induction heating, for the polymerization of said sealing substance.

5. A method according to claim 5, characterized in that said induction heating step is carried out for an interval of about 10 to 20 seconds.

6. A method according to any of the preceding claims, characterized in that said return pipe (1) is retained at a fixed position within said passage (3) during the subsequent three steps of the process.

7. A method according to any of the preceding claims, characterized in that the insertion of said return pipe (1) into said passage (3) is carried out so as to avoid any contact between the two components.

8. A method according to claim 7, characterized in that said space (12) has a width of between o.2 and o.5 mm.

9. A refrigerating appliance provided with at least one evaporator, characterized by being made with the employ of the method according to any of the preceding claims.

Description:

The invention relates to a method for fashioning a detail of an evaporator of the roll bond type for use in a refrigerating appliance, particularly of the domestic type, and to a refrigerating appliance equipped with an evaporator fashioned by employing this method.

The invention is in particular applicable to a refrigerator of the static function type or the forced circulation type, with a single capillary or twin capillaries. For the sake of simplicity, the following description will refer to the single-capillary type, it being understood, however, that the invention is similarly applicable to refrigerating appliances having more than one evaporator and a corresponding number of capillaries.
In refrigerant circuits for domestic refrigerating appliances of a known type, the capillary and the return pipe are connected to the evaporator by means of a "union" using a length of pipe, preferably aluminum pipe, to be inserted into a suitable cavity formed between the two aluminum sheets of which the well-known "roll bond" evaporator is composed.
As generally known, the employ of the roll bond technique permits the manufacture of the refrigerant circuit to be greatly simplified, although there are certain shortcomings known to those skilled in the art and relating to the method employed for making and connecting the evaporator.
As a matter of fact, in known refrigerating appliances equipped with a roll bond evaporator, the return pipe is compression-fitted thereto by exclusively mechanical means. This fitting technique is unable, however, to guarantee hermetic sealing at pressures of more than about 5 kp/cm<2>, so that under certain circumstances the high-pressure fluid tends to leak from the mechanic connection and to thereby escape from the refrigerant circuit.
The gravest inconvenience resulting from this technique is the possibility of the escape of gaseous refrigerant into the ambient atmosphere. This is because the connection of the return pipe to the return passage of the roll bond evaporator as well as the connection of the capillary to the are generally accomplished by the employ of well known procedures consisting in the compression from the outside of determined portions of the roll bond structure about the return pipe and the capillary at the locations of the return passage and the inlet pasage, respectively, of the roll bond evaporator.
This compression-fitting process may be accompanied by soldering the return pipe to the roll bond structure at the point of entrance, or by the application of an adhesive having suitable characteristics to the surface of the capillary and that of the return pipe at the respective compression-fitting locations.
The discussed shortcomings derive from the fact that the soldering operation is always a critical process with sometimes uncertain results, and in any case rather costly. For this reason the soldering method is whereever possible replaced by the application of adhesive at the compression-fitting locations.
On the other hand, however, the application of an adhesive to the surface of the return pipe to be inserted into the roll bond structure is not without problems caused for instance by the formation of bubbles in the thin adhesive coating or by the presence of adhesive-free areas resulting from the viscosity of the adhesive or from the adhesive being scraped off by mutual contact between complementary surfaces during the fitting process, which is usually a manual operation. Finally, the manual application of the adhesive may result in the presence of insufficient or excessive amount of adhesive on different surface areas, giving rise to faulty sealing.
The escape of the gaseous refrigerant cannot always be detected in the course of controls during the manufacturing process, particularly in the case of extremely small leaks. The full impact of the defect is thus noticed only after the refrigerating appliance has been put into use, requiring the manufacturer to carry out extremely onerous and laborious service operations, as well known by those skilled in the trade, without any remedy in sight.
The construction and maintenance of refrigerating appliances of this type are thus rendered rather complicated by the described operations which do not, moreover, lend themselves to being readily automatized.
It would therefore be desirable, and is in fact an object of the present invention, to provide a domestic refrigerating appliance in which the above discussed shortcomings are avoided without incurring construction complications or the necessity of novel technologies, so as to maintain low production costs.
These and other objects are attained in a refrigerating appliance as defined in the appended claims.
The invention will be more fully understood from the following description, given by way of example with reference to the accompanying drawings, wherein: fig. 1 is a diagrammatic illustration of a first step in the method according to the invention for sealingly connecting a return pipe to a roll bond evaporator, fig. 2 shows a second step of said method, and fig. 3 shows a third step of said method.

The method according to the invention is carried out in four distinct steps, the first one of which comprises the insertion of a return pipe 1, with a capillary 2 enclosed therein, into a passage 3 formed between the two sheet layers of a roll bond evaporator 4. The insertion of return pipe 1 into passage 3 has to be carried out in a manner ensuring that the two cylindrical elements are maintained substantially coaxial with one another, or at least with their respective surfaces out of contact with one another.
To this purpose the diameter of return pipe 1 is selected to be slightly smaller than that of passage 3, so that a space 12 of preferably about o.2 to o.5 is defined between the two respective surfaces.
As generally known, return pipe 1 is inserted to a predetermined position 5 of its inner end, while a certain length of capillary 2 projecting from the end of return pipe 1 extends through a restriction 6 formed in a linear extension 7 of return pipe receiving passage 3.
This positioning has to be maintained throughout the three subsequent steps of the operation, but then the operations of inserting the components and fixing them in position can be readily and fully automatised by one skilled in the art.
The second step comprises the compression of passage 3 about an end portion 8 of return pipe 1, and of restriction 6 about capillary 2, and is performed in the conventional manner.
The third step of the process comprises the injection of a semi-fluid substance having sealing and adhesive properties into a further passage 9 obtained by suitably shaping the two sheet layers of the roll bond structure. As clearly shown in the drawings, possage 9 has an outwards opening port 10 at one end, and at the other, a port 11 opening into the narrow space 12 defined between passage 3 of the roll bond structure and the length of return pipe 1 inserted thereinto.
It is important that port 11 opens into the bottom portion of space 12 as shown in the drawings.
The pressure applied for the injection of the semi-fluid substance is effective to ensure that the substance progressively and completely fills space 12 so as to fully replace the air originally contained therein, the length of space 12 having been selected with a view to achieving a reliable sealing effect.
It has thus been found that a length of space 12 of at least 30 mm is sufficient to ensure such reliable sealing effect to guard against gas losses, even when space 12 is not completely filled by the injected substance. Even when the air has not been completely displaced from space 12, leaving a small air pocket adjacent the closed end thereof, the desired sealing of the connection will not be impaired.
As a matter of fact, the hermetic sealing of the connection is substantially brought about by the injected adhesive substance forming an annular diaphragm between, and bonded to, the outer wall surface of return pipe 1 and the inner wall surface of passage 3, this diaphragm being impermeable to the passage of gas from one side thereof to the other.
The formation of an annular diaphragm having the above described sealing properties is ensured by the injection of the sealing substance through the port 11 located, as has been pointed out, closely adjacent the bottom of space 12.
It is preferable to employ a substance of the anaerobic polimerization type and of very low viscosity, and thus capable of penetrating even the smallest gaps of space 12 by capillary action.
Preferred in any case is the employ of a monocomponent anaerobic polymerization substance, for instance TOPFIX NA 84 supplied by CECA company, which requires a certain time for setting at least to a degree permitting the evaporator to be subsequently handled as for mounting it in a refrigerating appliance, without thereby endangering the previously obtained seal.
Since this time interval is usually not available in an automatized manufacturing process with high production rates, it is advisable to provide a fourth step which consists in performing a heat treatment of the area previously supplied with the sealing substance, preferably by subjecting the respective area to induction heating for a very short time, for instance 10 to 20 seconds, by the employ of a technique generally known to those skilled in the art.

At the end of this short period, the return pipe is perfectly sealed to the roll bond structure, so that the evaporator is ready for further processing.
The preceding description has been given on the assumption that the capillary 2 is contained within the return pipe 1. The teaching of the invention still holds valid, however, when the capillary 2 is to be connected to the evaporator independently of the return pipe.
The described method is thus conducive to obtaining the following advantages: a) Rapid establishment of the connection between the return pipe and the evaporator without the need for sealing gaskets or other auxiliary parts, and without the necessity of a soldering step, b) Simplified processing of the roll bond structure, c) Simplification and flexibility of the manufacturing process (to be carried out in separate steps capable of automatization), d) Overall economy of the manufacturing process. e) Above all, the quality of the connection is greatly improved as regards the obtention of a reliable seal, particularly with a view to not readily detectable slow leaks.
It is of course possible to design refrigerating appliances with modifications of what has been described above within the preview of the present invention.

Compressor ZANUSSI ELECTROLUX (VERDICHTER OE) V1040N R-12 110WATT. Compressor with hermetically sealed casing:

An electric compressor, particularly for household refrigerators, comprising an outside casing (1), an inside body (2), a cylinder head (3), a silencer (4) interposed between the cavity inside the compressor casing and the gas inlet pipe within the cylinder head (3), wherein the silencer (4) is substantially L-shaped, the greater side containing the expansion chamber (5) and the lesser side leading to the gas admission port (7) in the inlet valve and then to the outlet pipe (9) toward a Helmholtz resonator, the Helmholtz resonator being formed in the compressor body. The ratio between the area of the admission pipe (6) and the transverse section of the chamber (5) must be approximately 0.03, and the length of the chamber (5) must be approximately 34 mm.

1. An electric compressor, particularly for household refrigerators, comprising an outside casing (l), an inside body (2), a cylinder head (3), a silencer (4) interposed between the cavity inside the compressor casing and the gas inlet passage within the cylinder head (3), characterized in that in the chamber (5) inside the silencer (4) the ratio between the area of the admission pipe (6) and the transverse section of the chamber (5) is approximately 0.03, and the length of the chamber (5) is approximately 34 mm, the silencer (4) is substantially L-shaped, whereby the greater side contains the expansion chamber (5) and the gas admission pipe (6) into the chamber, and the lesser side constitutes the gas outlet pipe (8) from the chamber (5) and that the lesser side leads first to the gas admission port (7) in the inlet valve and then to the outlet pipe (9) toward a Helmholtz resonator.

2. The compressor of claim 1, characterized in that the Helmholtz resonator is formed within the compressor body.

3. The compressor of claims 1 or 2, characterized in that the expansion chamber (5) has two substantially parallel plane opposing walls and two curved opposing walls with the same direction and substantially the same angle of curvature.

4. The compressor of the preceding claim, characterized in that the silencer (4) has a constructional shape similar to a hook where the outlet pipe (9) is placed on the end-portion of said hook.

5. The compressor of any of the above claims, characterized in that the silencer (4) performs the function of reducing noise within an adiabatic change.

Description:

The present invention relates to a special form of inlet pipe for cooling gas inside an airtight enclosure containing an electric compressor, particularly employed in refrigerators for household use.
For better illustration of the present invention it is assumed that the pipe operates in close association with the compressor and that it is made of injection-molded or stamped plastic. This naturally does not limit the invention to this type of material and to this connection.
The fluctuations of gas pressure inside displacement compressors particularly for household refrigerators are of considerable importance in view of their influence on the efficiency and the level of acoustic power emitted by the compressors. Therein the cooling gas coming from the inlet pipe enters inside the airtight housing of the compressor.
The body of the compressor has an inlet pipe inside the casing connected to the inlet valve via various channels and cavities that permit the drawn-in gas to be conveyed inside the cylinder.

Being in contact with all the hot surfaces of the compressor, the gas heats up and reduces its density during these passages.
This leads to a reduction in the cylinder filling and thus ultimately to a reduction in the cooling capacity of the compressor.

The basic mechanisms regulating the dynamics of the gas movements are as follows.

1) The mechanism of restriction of flow through each "collar" and each connecting cavity constituting the system is regarded as an opening constricting the flow of gas. This effect is of virtually static character since the inertia of the gas is low, normally negligible, in the inlet and outlet passages which have reasonable dimensions.

2) The second mechanism is essentially of a dynamic nature, relating to the sudden opening and closing of the inlet and outlet valves. The sudden discharge of an amount of gas inside a cavity of the system causes an acceleration in the mass of the gas already existing in the passages downstream of the cavity, thus permitting the arriving gas to alter its thermodynamic characteristics minimally. The inertia of the gas offers resistance to this variation of motion and results in a pressure increase inside the cavity. Once this change of state has been established the gas persists in its motion (due to inertia), producing a rarefaction of gas in the cavity in which there was previously an overpressure. The repetition of this process, as is characteristic of reciprocating displacement compressors, produces a vibration of the gas. From the point of view of efficiency alone, the ideal solution would be the total elimination of any system of pipes, manifolds and cavities that have the function of collecting the gas upstream and downstream of the automatic valves.
However, maximizing thermodynamic efficiency in this way would accordingly increase the level of acoustic power emitted, particularly during intake, that is transmitted directly outside the casing of the compressor, thereby compromising the requirements of quietness.
It would therefore be desirable, and is the object of the present invention, to realize a compressor that combines high efficiency with low noise, and is reliable, economical and easy to assemble while using materials and techniques permitted by the state of the art.
This object is achieved with the device described, by way of example and nonrestrictively, with reference to the adjoined figures in which:

Fig. 1

shows a view of the inside of the compressor casing with the device shown from the front, comprising a silencer interposed between the intake of the gas from outside of the compressor and the cylinder head;

Fig. 2

shows a front inside view of the cover of the silencer;

Fig. 3

shows a lateral view of the same detail;

Fig. 4

shows a front inside view of the body of the silencer;

Fig. 5

shows a lateral section of the same detail.

The essential idea of the invention is described here as follows.
In order to maintain the process of gas intake within an adiabatic change (thereby preserving the cooling efficiency of the compressor), the acoustic control system is preferably made of plastic material.
An expansion silencer is realized between two pipes (having different sections) and by a Helmholtz resonator whose collar is positioned along the pipe at the outlet of the silencer on the side of the inlet valve.

Inside the silencer the spread of the acoustic waves is subject to interference and reflection phenomena that attenuate their acoustic intensity (understood to be the energy flow per unit of area).
Experiments have shown the transfer function of this component (understood to be the relation between an acoustic signal at the input and an acoustic signal at the output) when the silencer is subjected to an accidental-type acoustic signal, in static states and in air. The silencer has been found to be a low-pass acoustic filter, equipped with two resonances f1 and f2 (see Fig. 6).

 The attenuation of the acoustic intensity to resonant frequencies f1 and f2 is obtained by means of the Helmholtz resonator.
It is known that in systems composed of several weakly coupled components (silencer and resonator) the (generally complex) resonant frequencies are divided and shifted along the axis of the frequencies of a known range, so that one frequency is higher and one is lower than the frequency of the unmodified system.
Thus, if a resonator is applied to a cavity (and tuned to have the same natural frequency as an acoustic mode of the cavity), two new coupled modes are produced whose natural frequencies are disposed on the sides of the original frequency. The separation between the frequencies is proportional to the value of the coupling parameter.
To obtain good results with this type of coupling it is necessary to optimize the volume of the resonator in accordance with the volume of the cavity and also the position of the resonator neck, which must be located near a loop of the acoustic mode to be attenuated to a greater extent. It is therefore necessary to apportion these parameters to obtain a reduction of acoustic pressure at the starting frequency, whereby the reduction should be considerable but not excessive so as not to be compensated by a considerable increase of acoustic pressure to the two new frequencies that will be produced.
It is furthermore stressed that there is no flow of gas through the resonator cavity. Since there is thus no variation in the gas temperature due to the interposed cavity, the efficiency characteristics of the thermodynamic cycle are maintained unchanged.

The gas entering the compressor and coming from the inlet pipe is not dispersed in the casing to be then drawn into the inlet pipe present in the compressor body, but is immediately "intercepted" and directed toward the head without being allowed to spread.
For this purpose a silencer is designed and mounted for guiding the path of the gas and connecting on one side the area facing the gas entry port in the casing, and on the other side the inlet port in the cylinder head. The separation which the flow of gas thus undergoes and the particular path that develops achieve the result of preventing the gas from overheating and of blocking the intake noise within the pipe.

The features of the invention are specified in the claims that follow.
Referring to the figures we can see the following components:

1) compressor casing

2) compressor body

3) cylinder head

4) silencer, seen from its cover

5) expansion chamber of silencer

6) gas entry pipe into chamber 5

7) gas admission port in inlet valve

8) gas outlet pipe from chamber 5

9) outlet pipe to Helmholtz resonator Connected to head 3 of the compressor cylinder is intake silencer 4 made of plastic material, with gas entry port 6 and gas outlet pipe 8 from chamber 5, followed by port 7 toward the gas inlet valve in the head.

The cooling gas in pipe 6 enters chamber 5 inside silencer 4.
The silencer is interposed between the cavity inside the compressor casing and the gas inlet pipe within cylinder head 3, and is substantially L-shaped, whereby the greater side, widened at the center and virtually box-shaped, contains expansion chamber 5 and gas admission pipe 6 into the chamber, and the restriction of the lesser side constitutes gas outlet pipe 8 from chamber 5.
After the restriction the lesser side leads first to gas admission hole 7 in the inlet valve and then to outlet pipe 9 toward a Helmholtz resonator, consisting of a suitable cavity formed within the compressor body.
Expansion chamber 5 can have different forms, but preferably has two substantially parallel plane opposing walls and two curved opposing walls with the same direction and with substantially the same angle of curvature.
Chamber 5 can also have different forms provided that the following proportions are maintained between some critical dimensions.

The ratio between the area of admission pipe 6 and the transverse section of chamber 5 must be approximately 0.03.
Furthermore the length of cavity 5 must be approximately 34 mm.
In order to maintain the process of gas intake within an adiabatic change (thereby preserving the cooling efficiency of the compressor), the silencer is preferably made of plastic material.
It is understood that what has been said and shown with reference to the adjoined drawings is intended only to exemplify the invention, and that numerous variants and modifications may be produced without departing from the present invention as defined in the claims.

The compressor was originally designed by Bosch (Germany)
Verdichter Oe  in Fürstenfeld, Austria., the  largest producer of refrigeration compressors in the world with an annual production of 21 million compressors in its seven plants located in four continents.

Verdichter Oe History

1982	Project initiated by the Zanussi Group for a factory near Fürstenfeld, Austria, with the capacity of 1 million compressors per year. The name of the factory, "Verdichter", is the German word for "compressor".
1983	Start of production in one shift
1984	Start of production in two shifts
1986	Change of ownership (Electrolux Group buys Zanussi)
1988	Start of production in three shifts
1990	Production decrease (Massacre on Tian'anmen Square, less exports to China)
1994	Restart of production in three shifts
1995	Start of Flexible Shift System (including Saturday morning shift)
1996	Start of "Kappa" Project (Development of a new generation of compressors)
1998	Start of production 6 days x 24 hours a week
1999	Enlargement of factory buildings for Kappa production line

REX (ELECTROLUX)  IR023S Method of and apparatus for sealing tubes constructed of metals of high thermal and electrical conductivity:

 1. A method of welding together pieces constructed of metals of high thermal and electrical conductivity, wherein a piece to be welded is placed in contact with at least one electrode of negative temperature coefficient, so as to receive the heat energy which is developed therein when it is connected to a source of electricity.

2. A method as claimed in Claim 1, wherein the piece or pieces to be welded together are placed in contact with a pair of electrodes ol' negative temperature coeffici so as to establisll electrical continuity between said electrodes and receive the energy which is developed in these latter as a consequence of the establishment of the electrical continuity.

3. A method as claimed in the preceding Claims, wherein the electrodes are resiliently pressed on to the piece or pieces.

4. A method as claimed in the preceding Claims, wherein the welding is brazing.

5. A method as claimed in the preceding Claims, wherein the welding takes place as a result of plasticising.

6. A method as claimed In Claim 4, which is used for joining together elements of a refrigeration circuit, in particular a capillary tube and a tube of greater diameter.

7. A method as claimed in Claim 6, wherein the tiie tulle oi' greater diameter is previously deformed mechanically to provide a seati ii# i'c,r the capillary tube, and to form a socket region for receiving the brazing material

8. A method as claimed in Claim 4 and in one of the remaining Claims, wherein, at least llnti ] the moment in which the brazing material begins to melt, the intensity of the current circulating through the electrodes is kept at a higher value than during the time in which the electrodes are still maintained in contact witij at least one of the pieces to be joined together.

9. A method as claimed in Claim 8, wherein the intensity of the current circulating through the electrodes is decreased for at least part of the time subsequent to the moment in which the brazing material begins to melt, by connecting at least one resistive component in series with the electrodes.

10. A method as claimed in Claim 5 and one or more of the remaining claims, wllich is used for sealing a tube of a circuit containing a fluid under pressure.

11. A method as claimed in Claim 10, wherein the tube is meelBlically deformed on both sides of the weld before the weld is made.

12. An apparatus for carrying out the method as claimed in the preceding Claims, comprising at least one electrode ol' negative temperature coefficient, and means for connecting it to a source of electricity.

13. An apparatus as claimed in Claim 12, wherein the means izor connecting it to the source of electricity comprise the actual piece or pieces on which the electrode acts.

14. An apparatus as claimed in Claim 12 and/or 13, comprisillg a pair of electrodes of~ negative temperature coefficient which are mobile substantially in the same plane but in opposite directions, and between which the piece or pieces, used as tlie electrical connection means, are gripped

15. An apparatus as claimed in one or more of Claims 12 to 14, comprising a switch for connecting a resistive component I in series with the electrodes.

16. An apparatus as cm aimed in Claim 15, wherein the switch is controlled by a thermostat.

17. An apparatus as claimed in Claim 14, wherein at least one electrode is mounted resiliently yieldable in a mobile operating head wliicl, comprises at least one jaw for deforming the piece, in particular for mechanically closing a tube.

18. An apparatus as claimed in Claim 17, comprising two mobile heads and control means for moving said heads.

Description:

Method of and apparatus for welding together pieces constructed of metals of high thermal and electrical conductivity.
This invention relates to a method of welding together pieces constructed of metals, which can be different, but which have high thermal and electrical conductivity.
Although the invention can be applied to many fields, those of particular interest are a) joining a copper tube to an aluminium tube, for example in the refrigeration circuit oi' a domestic refrigerator, and b) sealing the copper tube through which the refrigerant fluid is charged into the refrigeration circuit of a domestic refrigerator.
In case a) , the copper tube can be the capillary tube and alluminium tube the evaporator and/or the suction tube of the compressor in the circuit. The capillary tube is that element of the refrigeration circuit in which the (theoretically isenthalpic) expansion occurs of the liquid refrigerating fluid whicli leaves the condenser to then enter the evaporator. As the undercooling of the capillary tube increases the useful effect of the refrigeration circuit, it is usual to insert a portion of the capillary tube in said suction tube.
It is therefore necessary to make at least one joint at the point in which the capillary tube enters the suction tube. A further joint is usually necessary at the point in wliic the capillary tube enters the evaporator, particularly if this latter is in the form of a tubular coil. As it must be ensured that the refrigeration circuit is absolutely hermetically sealed, the quality of the joints must be excellent, in spite of the difficulties due to tulle fact that the two pieces to be joined together are dii'ferent from each other, and have such a high electrical conductivity that it is impossible to make the joint by conventional resistance welding.

Again with reference to case a), a Jointing system is known which uses a short auxiliary copper tube having an outer diameter intermediate between the diameter of the capillary tube and the diameter of the aluminium tube. The capillary tube passes through said auxiliary tube, and is joined to one end thereof by torch brazing.
The other end of the auxiliary tube is joined to the aluminium tube by further brazing or by pressure welding.

This jointing system is certainly of good quality, but is relatively complicated and above all costly because of the copper construction of said auxiliary tube. The absolute value of this cost is very high when, in a modern industry, daily production amounts to several thousands of refrigerators.

With regard to case b), in the known method the copper charging tube is firstly closed by mechanical deformation using a clamp, and then, with the clamp applied, it is filled from its open end with a brazing material melted by means of a torch. This method has the disadvantage of not completely ensuring the opening of the welding zone, requiring the use of specialised labour and involving the use of a large quantity of brazing material when related to a daily production of several thousands of refrigerators.
The object of the present invention is to provide a new welding method, in particular for joining a copper capillary tube to an aluminium tube, and for closing the end of t}ie charging tube of a refrigeration circuit, in which low cost and simplicity of operation are attained together with excellent weld quality.
According to the method of the invention, a piece to be welded is placed in contact with at least one electrode having a negative temperature coefficient so as to recieve the heat energy developed in it when it is connected to a source of electricity.
In a preferred embodiment of the method ac cordillar to the invention, he piece or pieces to be welded together are placed in contact with a pair of electrodes having a negative temperature coefficient so as to establish electrical continuity between these electrodes and receive the heat energy which is developed in these latter as a consequence of establishing electrical continuity.
The term electrode having a negative temperature coefficient" indicates an electrode, the electrical resistallce of which decreases as the temperature increases.
The heat transmitted by the electrode or electrodes to the piece or pieces melts the welding material in contact with the piece, or at least transforms the piece into its plastic state so that, in this latter case, it is sufficient for the electrodes to exert a low pressure on the piece to form the weld.
The apparatus which enables the method to be carried out and is also part of the invention comprises at least one electrode of negative temperature coefficient, and meals lor connecting it to a source of electricity.
In the preferred embodiment of the apparatus, the mealls for connecting it to tulle source OS' electricity comprise the actual piece or pieces on which the electrode is to act.
In the most advantageous embodinlent of the invention, the apparatus comprises a pair of electrodes of Negative temperature coefficient, which are mobile sub staiitially in the same plane but in opposite directions, and between which are gripped the piece or pieces to be welded, these latter being utilised as the electrical connectioii means.
All the characteristics and advantages of the present invention will be apparent from the description given hereinafter (which, as a non-limiting example of application of this method, relates both to joining a copper capillary tube to an aluminium suction tube of the refrigeration circuit oi a domestic refrigerator by brazil and to sealing the end ol the charging' tube of such a refrigeration circuit) and from the accompanying drawing, in which:

: Figure 1 is a sectional diagrammatic view, through their axes, of two tubes during the operations involved in their joining; Figure 2 is a cross-section through said tubes on the line Il-Il of Figure 1 after the joint has been completed and the electrodes used have been removed; Figure 3 shows the electrical circuit used for melting the brazing material; Figure 4 shows the variations in the current intensity through the suction tube and its temperature adjacent to the electrodes during the joining by brazing; Figure 5 is a side view of the apparatus for welding (sealing) the charging tube of a refrigeration circuit; Figure 6 is a section on the line VI-VI of Figure 5, and Figure 7 shows a portion of the charging tube after its sealing.
With reference to Figures 1 and 2, a copper capillary tube 1 is inserted directly into a portion of an aluminium tube 2, for example representing the tube which constitutes the evaporator of a refrigeration circuit of a domestic refrigerator. There is thus a first great financial advantage in eliminating the aforesaid auxiliary copper tube. The aluminium tube 2 can have an outer diameter of 10 mm (against the 2 mm of the capillary tube 1), and has previously been mechanically deformed over a small portion 3 just after the mouth 4 to provide a flare 5 and a double lobed section at said portion 3 (see Fig. 2).
The brazing material and its de-oxidising agent are placed in the flare 5. These substances are indicated together by the reference numeral 6. The brazing material tried by the applicant in the example of the application of the method described here was the alloy known commercially as "So) dwiiol 1 265" of Messrs. Degussa ( the alloy carries the symbol L-CdZn 20, in accordance with D1N 1707). This is a eutectic cadmium-zinc alloy with Hs.5es of cadmium and a melting point of 266 C. The de-oxidising agent tried was wSoldaflux AL" of Messrs.
Degussa (carrying the symbol F-LW 3, in accordance with DIN 8511), its action being effective over the temperature range of 200 to 300 C.
According to the invention, the high conductivity of the aluminium with which the tube 2 is made is utilised to melt the brazing material. Thus the aforesaid technical and economical drawbacks due to the use of torch brazing are obviated. For this purpose, an electrical circuit (shown diagrammatically in Fig. 3) is constructed comprising the terminals 7 and 8 which receive an alternating single phase current from the secondary winding of a voltage step-down transformer (not shown), supply cables 9 and 10, and a pair of electrodes 11 and 12 of a material such as graphite which has a negative temperature coeffi cient. By the Joule effect, the electrical energy at the electrodes 11 and 12 is transformed into heat which reaches the brazing material by conduction through the tube 2.
These electrodes are brought into contact with the portion 3 of the tube 2 at the beginning of brazing. ln the electrical circuit diagrai ot' Fig. 3, the electrodes are shown as two variable resistor with the said reference numerals 11 and 12, whereas the reference numeral 13 indicates the resistance, obviously of extremely low value, of the tube 2 through which tulle circuit is made.
The circuit also comprises a switch 14 wlich, according to the control signals which it receives from the regulator 15, can be shifted from tulle contact 16 to the contact 17 to connect into the circuit a secondary branch 18 which comprises a high ohmic resist or 19.
The reglll ator 15 can be any device able to cause said resistor 19 to be connected in series with the electrodes 11 and 12 and tube 2 when the brazing material has reached its melting point, so reducing the current intensity l in the electrical circuit. In this respect, the applicant has fouiid that this lives an energy saving because the absorbed power of the circuit call be reduced by as much as 7596 during tlie second brazing stage (i.e.
when the switch 14 is closed on tlie contact 17) with respect to the first stage (i.e. when the switch 14 is closed on the contact 16). Advantageously, said regulator 15 is a rapid response thermostat, the sensor of which determines the temperature of the aluminium tube 2 in the immediate vicinity of the point in which it is joined to the capillary tube 1.
However, the regulator 15 can be in the form of a timer, provided it is known accurately after what time from the beginning of the operation the timer must shift the switch 14 from the contact 16 to the contact 17 (on the basis of all accurate trial run of the brazing operation).
The variation in current intensity I (measured in amperes) passing through the tube 2 during brazing, and the variation in temperature in C of this tube ( which can be sprayed with a conventional coolant after' brazing) shown in Figure 4 have been obtained by tests carried out by the applicant.
After the brazing material has melted, the electrodes 11 aiid 12 are removed from contact with the portion 3 of the tube 2, so that it is possible to remove this latter (now joined to the capillary tube 1) and proceed to a further brazing operation. In Figure 1 the approach and withdrawal of the tube electrodes are shown by arrows.
Fiiially, it silould be noted that in this example the el ectiodes do not exert any mechanical deformation action on the pieces to be joined together ( the tubes 1 and 2 in tills example). Thus(also because of the fact that the material of which the electrodes are made has a Ilegative tell1J#erature coefficient, i.e.
its electrical resistance decreases as its temperature increases) the method described herein is conceptually the opposite of collventional resistaiice welding of ferrous metals, which have a relatively high thermal and electrical conductivity.
The advalltages of the method according to the present invention can be suiirtriarised as follows: pieces made of materials of high electrical and thermal conductivity can be joined together by brazing other than torch brazing, and thus more simple to carry out and of much higher reliability; the energy consumption can be considerably reduced by not supplying excess energy when this is not required; in tlie particular case of joining a capillary tube to an aluniinium tube, it is no longer necessary to use an intermediate auxiliary tube.
With reference to Figures 5 to 7, which show the sealing of the tube for charging the refrigeration circuit of a domestic refrigerator with refrigerant fluid, the tube in question, constructed for example of copper, is indicated by the reference numeral 100. It is welded to the casing 101 which contains the compressor and its electrical drive motor (not shown), and communicates with the casing interior.
In order to introduce the refrigerant fluid, a connector element 102 incorporating a non-return valve 103 is mounted on the free end of tle tube 100 by well known methods. Again by well known methods, a charging pistol is connected to the connector element, and when operated causes pressurised refrigerant fluid to flow into the circuit. After the charging operation, the pistol is disconnected from the connector element, and the circuit then contains pressurised refrigerant fluid which cannot escape because of the non-return valve 103.
The problem solved by the invention is to properky seal the tube 100 after said charging operation, without usi)ig welding material.
According to the inventioll, the problem is solved by causing localised plasticising or fusion of the charging tube, mainly by the lleat given up by electrodes 104, 105 of negative temperature coefficient, for example of graphite, which are moderately pressed from opposing sides against the tube and thus cause permanent sealing of the tube by welding as a result of the plasticising or fus ioll .
Advai)te(J;eousiy, to prevent the pressurised refrigerant fluid iii the circuit from being able to escape through tlle passages wllic}l can open up in the plasticising or fusion zone, the tube is closed before welding and maintained closed during welding, by mechanical deformation exerted in a zone between the electrodes 104, 105 and the casing 101, and optiollally also in a zone between the electrodes and tulle free end of the charging tube.

The said operations are carried out by the device shown in Figures 5 to 7, comprising electrodes 104, 105 and means for localised temporary mechanical closure of the tube.
Tulle device in question comprises a pair of levers 106, 107 rotatable about their pivots 108, 109, and supported at their ends in a pair of parallel fixed side plates 110.
Each lever 106, 107 comprises at one end a working head 111 in which the electrode 104, 105 is disposed, and at the other end a roller 112 which, urged by springs 113, 114, is kept in contact with the end of a rod 115 of a piston 116. This piston is slidably mounted in a cylinder 117, and on one of its ends there acts a return spring 118 and on the other end there acts a pressurised fluid fed for example through a solenoid valve, not shown.
The end part 119 of the rod 115 is conical so that when the pressurised fluid is fed into the cylinder 117, the consequent movement of the piston 116 in the direction of the arrow A causes the levers 106, 107 to rotate in such a direction as to cause the working heads 111 to approach each other.
These heads comprise a fork structure with a pair of anns 12(), 121, the purpose of which is to deform the tube 100 at tlie two sides of the electrodes 104, 105 wheii the rod 115 is moved in the direction of the arrow A.
Each electrode 104, 105 is removably housed in a dovetail cavity 122 provided in a partly slotted metal block 123, with ducts 124 for the passage of cooling water ied through flexible hoses, not shown. Tlie block 123 is provided witlj a shank 125 of polyg'oiiai or square crosssection slidable in a bore of correspolldillg cross-section provided in tlie crosspiece 126 of tlse fork structure. The shank 125 comprises a head 127 against which a compression spring 128 acts,

its other end resting against a wall 129 rigid with the fork structure.
In the device concerned, the electrical circuit extends from the terminals B and C of an electricity source, through the electrodes 104, 105 and through the tube 100, when this latter is in contact with the electrodes.
The tube and electrodes are therefore in series when the device operates. The circuit is opened when the electrodes 104, 105 withdraw from the tube 100 following the return of the rod 115. Thus the welding operation, which will be discussed in greater detail hereinafter, can be controlled by the operator by operating the valve (e.g. a three-way valve) associated with the cylinder 117.
Operation is as follows: The two heads 111 are initially spaced apart from each other to allow the insertion of the tube 100 to be sealed (welded). When the tube is dosed between the heads, the operator feeds fluid under pressure to the cylinder 117. The rod 115 moves in the direction of the arrow A, the levers 106, 107 rotate about the pivots 108, 109, and the heads 111 approacl# the tube 100. The electrodes 104, 105 firstly touch the tube at the point N, but electricity is not as yet fed to the electrical circuit, even though this is ready to receive it.
The arms 120, 121 tlien act on the tube to deform it and close it mechanically in two zones K and M to tlie sides of the welding point N, this point being where the electrodes act.
The connector element 102 caii not be removed.
Electricity is now fed to the terminals B, C (e.g. by means of a contact) and flows in the circuit which is closed through the electrodes 104, 1()5 and tube 100. The electrodes 104, 105 progressively increase in temperature and thus heat point N to a sufficient extent to transform it into its plastic or partly molten state so that the small pressure wlsich the electrodes exert on the tube (by virtue of the springs 128) is sufficiei,# to produce deformation and corlsequent welding (when the opposing sides of the tube come into contact with each other).
On termination of welding (sealing), the operator unloads the cylinder 117, the two heads 111 withdraw from the tube and as the circuit is broken the electricity no longer traverses the electrodes 104, 105, which therefore cease to heat up.
The apparatus is thus ready for a new working cycle.
The present invention covers any other field of application of the described method, comprising the joining together of more than two pieces and the utilisation of the conductivity of all or some of the metals of which the pieces are constructed, to perform the welding, i.e. the fusion of the brazing materials.

REX (ELECTROLUX)  IR023S  , Device for inspecting the heat insulation of household appliances, more particularly refrigerators:

 1. In a plant for manufacturing a product including insulation material, said plant including means for forming the insulation material by foaming a polyurethane or similar material, thereby causing an exothermic reaction, and transport means for moving the product through said plant during the manufacture thereof, the improvement comprising means for inspecting the insulation characteristics of the insulation material, said inspecting means comprising:
thermographic means to be directed toward the product for, during said foaming, detecting a heat image of said insulation material as a function of said exothermic reaction and for generating detected coded data representative thereof;

processing and control means containing reference coded data representative of a heat image of insulation material of acceptable insulation characteristics and operatively connected to said thermographic means for receiving said detected coded data therefrom, for comparing said detected coded data with said reference coded data, and for generating coded response data as a function of such comparison; and
said processing and control means being operatively connected to said transport means for controlling the operation of said transport means as a function of said coded response data.


2. The improvement claimed in claim 1, wherein said processing and control means contains plural reference coded data representative of heat images of insulation material of acceptable insulation characteristics of respective different products, and further comprising input means operatively connected to said processing and control means for selecting a respective said reference coded data corresponding to a particular product to be manufactured.

3. The improvement claimed in claim 1, further comprising a monitor connected to said processing and control means for visually displaying said detected heat image.

4. The improvement claimed in claim 1, wherein said thermographic means is capable of orientation toward plural different areas of the product.

5. The improvement claimed in claim 1, wherein said transport means comprises a conveyor for moving products through said plant, and further comprising an auxiliary conveyor for conveying defective products, said processing and control means causing said conveyor or said auxiliary conveyor to operate as a function of said coded response data being respectively within or without a predetermined range.

6. The improvement claimed in claim 1, further comprising at least one additional thermographic means, and means for selectively switching said thermographic means and said at least one additional thermographic means into and out of operative connection with said processing and control means.

7. The improvement claimed in claim 1, wherein said thermographic means is connected to said processing and control means by an interface.

8. The improvement claimed in claim 7, wherein said thermographic means further is connected to said processing and control means by an analog/digital converter.

9. The improvement claimed in claim 1, wherein said processing and control means is connected to said transport means by an interface.

10. The improvement claimed in claim 9, wherein said processing and control means further is connected to said transport means by a digital/analog converter.

11. An inspecting device, for use in a plant for manufacturing a product including insulation material, said plant including means for forming the insulation material by forming a polyurethane or similar material, thereby causing an exothermic reaction, and transport means for moving the product through the plant during the manufacture thereof, means for inspecting the insulation characteristics of the insulation material, said inspecting means comprising: thermographic means to be directed toward the product for, during the foaming operation, detecting a heat image of the insulation material as a function of said exothermic reaction and for generating detected coded data representative thereof;
processing and control means containing reference coded data representative of a heat image of insulation material of acceptable insulation characteristics and operatively connected to said thermographic means for receiving said detected coded data therefrom, for comparing said detected coded data with said reference coded data, and for generating coded response data as a function of such comparison; and
said processing and control means including means to be operatively connected to the transport means for controlling the operation of the transport means as a function of said coded response data.


12. A device as claimed in claim 11, wherein said processing and control means contains plural reference coded data representative of heat images of insulation material of acceptable insulation characteristics of respective different products, and further comprising input means operatively connected to said processing and control means for selecting a respective said reference coded data corresponding to a particular product to be manufactured.

13. A device as claimed in claim 11, further comprising a monitor connected to said processing and control means for visually displaying said detected heat image.

14. A device as claimed in claim 11, wherein said thermographic means is capable of orientation toward plural different areas of the product.

15. A device as claimed in claim 11, wherein said thermographic means is connected to said processing and control means by an interface.

16. A device as claimed in claim 15, wherein said thermographic means further is connected to said processing and control means by an analog/digital converter.

17. A device as claimed in claim 11, further comprising an interface for connecting said processing and control means to the transport means.

18. A device as claimed in claim 17, further comprising a digital/analog converter for further connecting said processing and control means to the transport means.

19. A device as claimed in claim 11, wherein the transport means comprises a conveyor for moving products through said plant and auxiliary conveyor for conveying defective products, and said processing and control means causes the conveyor or the auxiliary conveyor to operate as a function of said coded response data being respectively within or without a predetermined range.

20. A device as claimed in claim 11, further comprising at least one additional thermographic means, and means for selectively switching said thermographic means and said at least one additional thermographic means into and out of operative connection with said processing and control means.

21. In a process for manufacturing a product including insulation material, said process including forming the insulation material by foaming a polyurethane or similar material, thereby causing an exothermic reaction, and moving said product by transport means during the manufacture thereof, the improvement comprising inspecting the insulation characteristics of said insulation material, said inspecting comprising: directing thermographic means toward said product and thereby, during said foaming, detecting a heat image of said insulation material as a function of said exothermic reaction and for generating detected coded data representative thereof;
providing processing and control means containing reference coded data representative of a heat image of insulation material of acceptable insulation characteristics;
delivering said detected coded data from said thermographic means to said processing and control means and therein comparing said detected coded data with said reference coded data and generating coded response data as a function of such comparison; and
controlling the operation of said transport means as a function of said coded response data.


22. The improvement claimed in claim 21, comprising provided said processing and control means with plural reference coded data representative of heat images of insulation material of acceptable insulation characteristics of respective different products, and inputting to said processing and control means a selected respective said reference coded data corresponding to a particular product to be manufactured.

23. The improvement claimed in claim 21, further comprising visually displaying said detected heat image on a monitor connected to said processing and control means.

24. The improvement claimed in claim 21, further comprising orienting said thermographic means toward plural different areas of said product.

25. The improvement claimed in claim 21, wherein said transport means comprises a conveyor for moving products and an auxiliary conveyor for conveying defective products, and further comprising causing said processing and control means to operate said conveyor or said auxiliary conveyor as a function of said coded response data being respectively within or without a predetermined range.

26. The improvement claimed in claim 21, further comprising providing at least one additional thermographic means, and selectively switching said thermographic means and said at least one additional thermographic means into and out of operative connection with said processing and control means.

27. The improvement claimed in claim 21, comprising connecting said thermographic means to said processing and control means by an interface.

28. The improvement claimed in claim 27, further comprising connecting said thermographic means to said processing and control means by an analog/digital converter.

29. The improvement claimed in claim 21, comprising connecting said processing and control means to said transport means by an interface.

30. The improvement claimed in claim 29, further comprising connecting said processing and control means to said transport means by a digital/analog converter.

31. The improvement claimed in claim 21, wherein said product is a household appliance and said insulation material is thermal insulation.

32. The improvement claimed in claim 31, wherein said product is a refrigerator.

Description:

BACKGROUND OF THE INVENTION
The invention relates to a device for inspecting the heat insulation of household appliances, more particularly refrigerators, such device being capable of detecting immediately and in a simple manner any deficiencies in the heat insulation during the manufacture of the appliances.
Nowadays, the mass production of a household appliance such as a refrigerator comprises the prefabrication of the body thereof in the form of a metal cabinet which is of substantially parallelepipedal shape and is open on its front side, and of a plastic cell of traditional type dimensioned to fit within such cabinet so as to define therewith an intervening space adapted to receive heat insulation.
The body, in turn, is provided with suitable fixtures for the attachment of a closure door on the front side of the cabinet, such door likewise being of parallelepipedal shape and comprising an outer metal covering and an inner door of plastic material, which elements can be fitted together so as to define an intermediate space adapted to receive heat insulation.
In practice, each door of the refrigerator is made separately from the corresponding body and each of these components is then transported separately by means known per se on a conveyor belt of an assembly line for carrying out processing steps adapted to produce, one after the other, the heat insulation of the body and of the door, as well as the assembling of the body with the door and with other operating components of the refrigerator.
In particular, this heat insulation is obtained by means of polyurethane materials which are known per se, and the liquid components of which are injected separately by traditional apparatus provided along the conveyor belt involved within the corresponding intermediate spaces in the body and the door, in which spaces such components polymerize (so-called foaming operation) and spread out in such a manner as to occupy all of such intermediate spaces.
In order to be able to carry out the foaming operations of the refrigerators satisfactorily, without defects being present in the heat insulation of such appliances, it is necessary that the equipment involved be caused to operate under the same operating and environmental conditions throughout the foaming operation and, furthermore, that the areas of injection of the bodies and doors of the respective refrigerators permit the effective penetration of the polyurethane material into the respective intermediate spaces of the bodies and doors.
In practice, however, such equipment is subject to operating and environmental conditions which at times vary during the foaming of the appliances in question, while the areas of injection of the polyurethane material themselves can, at times, have structural defects such as partly to prevent the penetration and proper distribution of the material throughout the above-described spaces.
Accordingly, under such conditions, defects may appear in the heat insulation of the refrigerators, due primarily to the presence of areas which are without polyurethane material (continuous and non-continuous holes) and areas in which such material is not completely polymerized (so-called "exhausted foam"), which defects result in a decrease of the insulating power of the layer of material and, in certain cases, even in the formation of heat bridges which significantly impair the functionality of the product.
At the present time, the presence of any defects of this type in the heat insulation of refrigerators is detected by the workers during the manufacture of these appliances by means of a number of visual and manual inspections in the areas of the appliances themselves in which such defects are most likely to be located.
While, on the one hand, this type of inspection makes it possible to single out practically all appliances that have defects located in areas which are directly noticeable from the outside, so that it is possible to discard such defective appliances or to perform operations thereon aimed at eliminating the defects found, this method is not, on the other hand, completely reliable in that it does not enable one to accurately examine the entire structure of the heat insulation and thus to single out any defective areas which are found in the insulation itself or which are difficult to locate by the inspections indicated above.

SUMMARY OF THE INVENTION
Therefore, it would be desirable, and this is the object of the present invention, to provide for a device for inspecting the heat insulation or insulation characteristics of household appliances such as refrigerators, which device can immediately and automatically detect the possible presence of defects of any kind and size in the insulation during the production stages of these appliances, thereby obtaining a thorough check of all the appliances manufactured and making it possible to eliminate, or possibly repair, defective appliances.
This inspection device is essentially based on the use of at least one traditional thermographic apparatus for detecting the images produced by the heat insulation of the refrigerators as well as comparing the coded data obtained by such apparatus with other coded data corresponding to optimal functional conditions of the heat insulation, so that from such comparison the presence of any defects of the insulation can be detected immediately.
This technique of detecting thermographic images is used at present in combination with any preexisting type of heat insulation and provides for the detection by the thermographic apparatus of heat radiation passing through the insulation and produced by a suitable separate heat source.
The thermographic images thus produced are visible on the screen of a monitor associated with the apparatus and produce colors of different intensity, depending on the defective areas and on the areas with different densities of the heat insulation.
The present inspection system, however, makes it possible to point out the heat images of the insulation by utilizing the thermal radiation produced by the insulation during its foaming as a result of the corresponding chemical reaction, rather than that produced by a separate heat source as in the past.
These and other objects are achieved, in accordance with the invention, by means of a device for inspecting the heat insulation of household appliances, more particularly refrigerators, which can be used in combination with a plant for the manufacture of such appliances and including means for the foaming of the heat insulation of the appliances by use of polyurethane or similar materials as well as means for the transportation of the appliances. The device includes at least one thermographic apparatus associated with any monitor of traditional type in order to detect the thermographic images of the insulation.
The inspection device also includes at least one control and processing unit known per se containing a series of coded reference data corresponding to the correct production of the heat insulation of each type of household appliance to be produced. The control and processing unit is connected to the thermographic apparatus, to the conveyor means and to at least one input unit known per se for selecting the coded reference data corresponding to the model of household appliance which is to be produced in order to input such coded data into the control and processing unit with the object of comparing it with the coded data supplied by the thermographic apparatus and corresponding to the thermographic images detected thereby, in the presence of the exothermic reaction of the material of the heat insulation during its foaming. The control and processing unit supplies, as a result of such comparison, coded response data adapted to control the conveyor means.

BRIEF DESCRIPTION OF THE DRAWING
Other aspects of the invention will become more apparent from the ensuing description given solely by way of non-limiting example, reference being had to the accompanying drawing which diagrammatically shows the inspection device of the invention used in combination with a traditional manufacturing plant for household refrigerators.

DETAILED DESCRIPTION OF THE INVENTION
Now, with reference to the drawing, it shows the present device for inspecting the heat insulation of household appliances, in the present example refrigerators, which can be assembled in a manufacturing plant comprising at least one traditional apparatus 1 for the foaming of heat insulation by means of polyurethane or similar materials, and also comprising a transport means such as a conveyor belt 2 of known construction. Conveyor belt 2, in particular, can be driven with a continuous forward motion by drive mechanisms known per se denoted diagrammatically by the reference numeral 3, so as to permit the transportation and assembly of the various elements constituting each refrigerator, that is to say, the body 4 and the door 5.
Each body 4 is formed, as in the prior art, of a metal cabinet 6 which is of a substantially parallelepipedal shape and has dimensions which may vary from one appliance model to the next, cabinet 6 being open on its front side and being adapted to contain a plastic cell 7 of traditional type dimensioned such as to fit perfectly within cabinet 6, in order to define therewith an intermediate space 8 in which the heat insulation is foamed.
Each door 5, in turn, is also of parallelepipedal shape and is formed of an outer metal covering 9 and an inner door 10 of plastic, the shapes of both being adapted to each other so as to define an intermediate space 11 into which the heat insulation is foamed.
As an alternative, the transportion and assembly of the constituent parts of each refrigerator could also be effected by at least one fully automated production line, comprising any possible manipulators 12 or similar apparatus of known construction.
The inspection device incorporating the invention is essentially comprised of at least one traditional thermographic apparatus 13, such as a pyroelectric television camera, a pyrometer or similar sensor adapted to detect heat images of the heat insulation so as directly to evaluate the condition thereof, utilizing the exothermic reaction of the material of such insulation during its foaming.
Preferably, the spectral sensitivity of the television camera or of the sensor in question will be within the region of infrared radiation, with wavelengths equal to those of transparency of the plastic materials used for the construction of the refrigerator bodies and doors, in order to be able to obtain heat images with good definition of the insulation. Such thermographic apparatus, in particular, is connected to an electric power supply and is arranged alongside the heat insulation of the refrigerators located on the conveyor belt 2.
Furthermore, such apparatus can be oriented in different positions with respect to the body and door of each refrigerator so as to be able selectively and accurately to check all those areas of the heat insulation of these constituent parts which have the greatest probability of being defective during manufacture.
As will be apparent from the drawing, the apparatus in question detects the heat images by being aimed exclusively at the respective parts of the body and door of plastic or other material with medium or low heat conductivity in which there is the minimum distribution of heat on the surface as compared with what takes place in the case of metal surfaces.
In addition, the present inspection device comprises at least one control and processing unit 14 made up of a microcomputer, a personal computer or some other processing apparatus of known construction, such unit being connected to the thermographic apparatus 13 by at least one interface 15 and an analog/digital converter 16 of known construction.
In the control and processing unit 14 there has been previously stored data coded in digital form corresponding to reference thermal maps of the heat insulation of each model of refrigerator which is to be manufactured.
In particular, each thermal map is obtained experimentally on a series of models of refrigerators and corresponds to a condition under which the heat insulation of such appliances is produced properly, without the presence of defective areas and under pre-established operating and environmental conditions.
Moreover, control and processing unit 14 is possibly connected to at least one monitor 17 of traditional type for the visual display of the thermographic images of the heat insulation detected by the thermographic apparatus described earlier, and it is also connected to at least one input unit 18 made up of a keyboard or other peripheral equipment of known construction (e.g., bar code readers).
The purpose of the input unit 18 is to select coded data corresponding to the reference thermal map relative to the model of refrigerator (or other household appliance) which is to be produced, in order to input such coded data into the control and processing unit 14 so that said such reference thermal map can be compared therein with the thermal map found on each refrigerator manufactured by the procedure described hereinafter.
Furthermore, the input unit 18 makes possible the introduction of further reference thermal maps in coded form into the control and processing unit 14, whenever other models of refrigerators (or other household appliances) are produced.
In this way, as soon as the thermographic apparatus 13 finds or determines a thermographic image of the area to be checked of the heat insulation of the refrigerator body or door during the course of production thereof, which image is visible to the operator on the monitor 17, if provided, thermographic apparatus 13 produces data coded in analog form which corresponds to such image and which is converted into digital form by the analog/digital converter 16 and sent to the control and processing unit 14. This coded data is then compared in the unit 14 with the coded data corresponding to the relevant reference thermal map previously stored in unit 14 in order thereby to be able to verify whether the heat insulation in question has been produced properly and is without manufacturing defects that could reduce its insulating power.
In practice, if such comparison shows minimum differences between the corresponding coded data of the heat image found or determined and the reference map in question, which differences are, however, within a preestablished range of tolerance corresponding to the proper production of the heat insulation, then the control and processing unit 14 proceeds to process corresponding coded response data in digital form, which may be converted into analog form by a digital/analog converter 19 and sent to an interface 20 adapted to control the drive mechanisms 3 and thereby to cause the conveyor belt 2 to move forward.
Accordingly, under these circumstances, the assembling of the refrigerator which has thus been inspected can be completed.
Conversely, if the comparison between such coded data shows differences that do not fall within the specified range of tolerance, the control and processing unit 14 proceeds to process corresponding response data which are adapted to control, by the same procedures described earlier, another drive mechanism 21 which is associated with an auxiliary conveyor belt 22 so as to enable repair work to be performed on the defects found, for instance further foaming of the heat insulation or, if this is not possible, transporting the defective appliances for scrapping or replacement.
Similarly, if the refrigerator manufacturing plant consists of mechanical manipulators 12 or other apparatus for automatic assembly instead of conveyor belts, the control and processing unit 14 proceeds to control such manipulators under the same criteria and for the same purposes as described above. Therefore, the inspection device of the invention makes it possible to find in a simple, immediate and automatic manner any defect in the heat insulation of the appliances produced, thereby achieving a complete inspection of all the appliances and the maximum degree of reliability of the plant for their manufacture, and furthermore permitting the elimination or repair of defective appliances.
The present inspection device can, of course, also be combined with plants for the manufacture of products other than those described herein, for instance for producing slabs of acoustic or thermal insulating materials, etc., their essential characteristics being that they develop an exothermic reaction during manufacture.
Finally, it should be pointed out that the inspection device of the invention can also be provided with further thermographic apparatus 13 which can be switched selectively with the control and processing unit 14 by means known per se (e.g., a multiplexer or the like) and arranged along different areas of the heat insulation of one or more appliances during the course of manufacture thereof.

Electrolux AB History:

Electrolux AB operates as the largest appliance manufacturer in the world with customers in more than 150 countries. The company manufactures a variety of household appliances including refrigerators, washing machines, dishwashers, ovens, vacuum cleaners, lawn mowers, and chain saws. The firm also manufactures professional foodservice and laundry equipment used by hotels, restaurants, and laundromats. Electrolux's brand arsenal includes its namesake, along with Eureka, AEG, Frigidaire, Kelvinator, Zanussi, Flymo, Weed Eater, and Husqvarna. In 2001, the firm held the leading market position in North America, Europe, Latin America, and Australia. Electrolux completed a major restructuring effort in 1999, which left it positioned with two main business segments: Consumer Durables and Professional Products. In 2000, the company purchased the rights to market the Electrolux brand in the United States--the company had sold the brand along with its U.S. floor-care business in 1969.

Key Dates:

1919:
    Lux and Elektromekaniska merge to form Aktiebolaget Elektrolux.
1921:
    The Lux V vacuum cleaner is introduced.
1925:
    The company acquires Arctic, an absorption refrigerator manufacturer.
1956:
    Axel Wenner-Gren sells his stake in the firm to Wallenberg, a Swedish finance group.
1957:
    The company changes the spelling of its name to Electrolux.
1962:
    ElektroHelios, a Scandinavian market leader in compressor refrigerators and freezers, is acquired.
1967:
    Hans Werthén is named president.
1974:
    Electrolux purchases United States-based Eureka.
1984:
    Zanussi, an Italian household appliance manufacturer, is acquired.
1997:
    Michael Treschow is named president and CEO; a major restructuring effort is launched.
2000:
    The company buys the rights to the Electrolux brand in North America.
2002:
    Treschow leaves to head up Ericsson; Hans Straberg is named his successor.



Beginnings in Vacuum Cleaners

The Electrolux empire originated with the perspicacity and marketing flair of Axel Wenner-Gren, who spotted the potential of the mobile vacuum cleaner only a few years after its invention by Englishman H.C. Booth in 1901. In 1910 the young Wenner-Gren bought a part share in the European agent of a U.S. company producing one of the early vacuum cleaners, the clumsy Santo Staubsauger. After a couple of years as a Santo salesman for the German-based agent, Wenner-Gren sold his share of the company and returned to Sweden, where the building blocks for the future Electrolux, Lux and Elektromekaniska AB, were already in place.

Sven Carlstedt had formed Elektromekaniska in 1910 to manufacture motors for a vacuum cleaner based on the Santo, which was produced by Swedish engineer Eberhardt Seger. Since its founding in 1901, Lux had manufactured kerosene lamps. Now confronted with a shrinking market owing to the introduction of electric lighting, Lux head, C.G. Lindblom, proposed to Sven Carlstedt that the two companies form a joint venture for the production and marketing of a new vacuum cleaner.

In 1912 Wenner-Gren became the agent for the Lux 1 vacuum cleaner in Germany, subsequently taking on the United Kingdom and France. Over the next few years Wenner-Gren's role in the company grew, and the machine gradually became lighter and more ergonomic. Wenner-Gren foresaw a potential sales bonanza in Europe after the end of World War I. Initially unable to persuade his colleagues to step up production capacity, he overcame their reluctance by guaranteeing a minimum sales figure through his own sales company, Svenska Elektron (later known as Finans AB Svetro).

Lux and Elektromekaniska merged in 1919 as Aktiebolaget Elektrolux (the spelling was changed to Electrolux in 1957). Wenner-Gren became president and a major shareholder of the new company. In 1921 the Lux V was introduced. This new model resembled a modern cylindrical vacuum cleaner, but it glided along the floor on ski-like runners instead of wheels. The Lux V was to present serious competition to the upright Hoover machines in the 1920s.

The convenience and attractive styling of its product helped to get the new company off to a promising start, but the salesmanship of Electrolux's president probably played an even bigger part. Wenner-Gren was a great believer in the door-to-door sales techniques already espoused by competitors such as Hoover in the United States. Vacuum cleaners were demonstrated to potential customers in their own homes, and buyers were allowed to pay for their machines in installments. Wenner-Gren knew how to get the best out of his sales force.

To today's sales managers, sales training, competitions, and slogans like "Every home an Electrolux home" are familiar methods of boosting sales, but when Wenner-Gren introduced them they were revolutionary. He also believed in leading from the front. The story of how he sold a vacuum cleaner to the Vatican is part of company mythology. Four competitors demonstrated their machines first, each vacuuming their allocated area of carpet. When Wenner-Gren's turn came, instead of vacuuming the fifth area, he went over the first four again. The resultant bagful of dust persuaded the pope to add his palace to the growing number of Electrolux homes. Advertising, too, was imaginative. Not only did Electrolux make extensive use of the press, but in the late 1920s, citizens of Stockholm, Berlin, and London were liable to encounter bizarre vacuum cleaner-shaped cars in the streets.

Bizarre or not, the sales methods worked, and the company grew. Throughout the 1920s, new sales companies sprang up, not only all over Europe but also in the United States in 1924, Australia in 1925, and South America. Many of these were financed by Wenner-Gren himself rather than by Electrolux in Sweden. Vacuum cleaner manufacturing plants also started to open overseas, first in Berlin in 1926 and a year later in Luton, England, and Courbevoie, France.

By 1928 Electrolux had sales of SKr 70 million. It had five manufacturing plants, 350 worldwide offices, and 20 subsidiaries. In spite of this geographic expansion, the company was often short of funds, in part because of the system of payment by installments. It became clear that further growth would require increased capital, and it was decided to float the company on the London Stock Exchange and to issue more shares. Prior to flotation in 1928, Electrolux bought out many of the related companies owned by Wenner-Gren, though he retained his minority shareholding in the American Electrolux Corporation until 1949.

Flotation on the Stockholm stock exchange was postponed until 1930 owing to the stock market crash. When the shares did appear they were greeted with some mistrust, as it was thought that the company was overvalued and that sales would suffer during the anticipated recession. These doubts, however, were to prove unfounded.

Diversifying into Refrigerators in the Mid-1920s

During the 1920s Electrolux introduced a number of new products, including floor-polishers, a natural progression from vacuum cleaners, which were brought out in 1927. The main diversification of the 1920s, however, came through the acquisition in 1925 of Arctic, a company manufacturing a novel machine, the absorption refrigerator. This type of refrigerator has no moving parts, though early models required connection to a source of running water. Power can be provided by electricity, gas, or kerosene as opposed to the compression method of refrigeration, which relies on electric power. Early compressors were noisy and bulky, so the new Electrolux system had several advantages over its competitors' compression refrigerators.

A new air-cooled version of Electrolux's absorption refrigerators was introduced in 1931, and by 1936 more than one million had been sold. Demand for the machines grew as restrictions were placed on the use of food preservatives by legislation such as the United Kingdom Food Preservative Act of 1927. In the United States, Servel Inc. had acquired a license to manufacture Electrolux's refrigerators.

Electrolux's original vacuum cleaner factory on Lilla Essingen was devastated by fire in 1936. When it was rebuilt the following year, the opportunity was taken to fit it with the latest equipment and to install a central research laboratory.

In 1926 Wenner-Gren became chairman of the board, with Ernst Aurell taking over as president. During the 1930s Wenner-Gren remained chairman but reduced his involvement in the running of the company, prior to resigning from his post in 1939. Harry G. Faulkner, a British accountant who had been instrumental in the company's consolidation prior to the 1928 flotation, succeeded Aurell in 1930 and remained president throughout the 1930s.

With intensive marketing and continued investment in research and development, Electrolux rode out the Great Depression. By 1939 annual sales stood at SKr 80 million. In 1939 Gustaf Sahlin, former president of the United States Electrolux Corporation, took over the presidency of the parent company from Faulkner. Throughout World War II, despite the loss of some manufacturing plants, Electrolux managed to maintain many of its usual activities, opening operations in Australia, Venezuela, and Colombia. At home in Sweden, it acquired companies in the fields of commercial laundry equipment and outboard motors. Much energy, however, was diverted into the war effort, including the manufacture of munitions and of air cleaners for the Swedish forces.

After the war Electrolux resumed its normal operations, initially under Elon V. Ekman, who became president in 1951, and from 1963 to 1967 under his successor Harry Wennberg. The period was not without setbacks, however. Many subsidiaries that had been opened in Eastern European countries before the war disappeared from view behind the Iron Curtain. In addition, despite a British government contract to supply 50,000 built-in absorption refrigerators for prefabricated temporary houses, the company began to face problems in the refrigerator market. Compression technology had advanced and was proving more effective for the larger refrigerators that consumers were now demanding. Although at first the company concentrated on improving the design of the absorption refrigerator, Electrolux eventually was obliged to adopt compression technology.

Meanwhile, diversification continued. During the 1950s Electrolux started making household washing machines and dishwashers, and floor-cleaning equipment production was extended to an increasing number of countries, including Brazil and Norway. When, in 1956, Axel Wenner-Gren sold his remaining shares in Electrolux to Wallenberg, a Swedish finance group, annual turnover exceeded SKr 500 million. The association with Wallenberg has often stood Electrolux in good stead, helping, for example, to arrange overseas funding and to insulate the group from any hostile takeover bids.

In 1962, in an attempt to solve its refrigerator problems, Electrolux bought the Swedish firm of ElektroHelios. This firm, founded in 1919, had a major share of the Scandinavian market in compressor refrigerators and freezers, as well as making stoves. In the year following the acquisition, Electrolux launched a wide range of food-storage equipment, putting it in a strong position to benefit from the demands generated by the flourishing frozen food industry.

Major Acquisitions: Late 1960s-80s

Until the 1960s Electrolux had continued to operate along the lines conceived by Wenner-Gren in the early years. A new phase began in 1967, when Hans Werthén was recruited from Ericsson, another member of the Wallenberg group of companies. Werthén remained with Electrolux for more than 25 years, first as president, and from 1975 to 1991 as chairman, with Gösta Bystedt and then Anders Scharp succeeding him as president. Under this regime, a series of momentous acquisitions was to allow Electrolux to multiply its turnover by a factor of 60 in 20 years.

When Werthén took over management of the Electrolux group the company was in the doldrums; it had run into internal and external problems, and its technology was outmoded. Electrolux, an international company, had not been effectively integrated with its acquisition ElektroHelios, which still focused on the Scandinavian market. In many ways the merged companies had continued to behave as if they were still competitors, resulting in a net loss of market share in the refrigerator market. Only the vacuum cleaners were profitable: to use Werthén's own words, "they represented 125 percent of the profits."

Approaching the problem from a new perspective, Werthén managed to resolve the Electrolux-ElektroHelios conflict and get rid of the organizational overlap. His new head of production, Anders Scharp, set about updating production technology to challenge the much more advanced techniques he had seen in U.S. appliance factories. Werthén believed that Electrolux's problems could not be overcome simply by operational improvements. The company had a more fundamental problem: size.

As Werthén saw it, Electrolux was neither small enough to be a niche player, nor large enough to gain the economies of scale it needed to compete with such giants as Philips and AEG. Growth was the only way forward, and in the overcrowded market place for household goods, growth meant acquisitions.

The initial focus was on Scandinavia. One small competitor after another, many of them struggling for survival, was bought up by the growing company. The Norwegian stove manufacturer Elektra, the Danish white goods company Atlas, and the Finnish stove maker Slev were among the first acquisitions of the late 1960s. Soon Electrolux was shopping for competitors outside Scandinavia. The 1974 acquisition of Eureka, one of the longest established vacuum cleaner companies in the United States, gave Electrolux a large slice of a valuable market overnight.

At around this time there were glimmerings of hope for the reemergence of the absorption refrigerator. The quiet-running units were ideally suited to installation in smaller living spaces, such as mobile homes and hotel rooms. Electrolux managers soon sensed these new opportunities. After taking over competitors Kreft (of Luxembourg) and Siegas (of Germany) in 1972, the group became world leader in this sector.

In addition to expanding its share of the company's existing markets, Electrolux soon started to see acquisitions as a way of entering new areas, particularly those related to existing product lines. Electrolux acquired the British lawn mower manufacturer Flymo in 1968 because Werthén saw lawn mowing as an activity allied to floor cleaning. The provision of cleaning services seemed a logical extension to the production of cleaning equipment, prompting the purchase of a half share in the Swedish cleaning company ASAB.

Buying up the venerable Swedish firm of Husqvarna in 1978 gave Electrolux not only a new pool of expertise in commercial refrigeration, but also a flourishing chainsaw-manufacturing concern, which complemented its interests in outdoor equipment. Taking over a clutch of other chainsaw manufacturers over the following decade--including the U.S. firm Poulan/Weed Eater in 1986--enabled Electrolux to claim leadership of the worldwide chainsaw market. The outdoor products sector was further strengthened and broadened through the acquisitions of American Yard Products in 1988 and of Allegretti & Co., a U.S. maker of battery-driven garden tools, in 1990.

This program of acquisitions brought some more radical departures from existing product lines. In 1973 Electrolux bought Facit, a Swedish office equipment company. The deal also brought to Electrolux the production of Ballingslöv kitchen and bathroom cabinets. Initial doubts about whether Electrolux had the know-how to manage a high-tech company proved unfounded.

The purchase of Swedish metal producer Gränges was greeted with equal skepticism, since again the connection between the new and existing businesses appeared to be rather tenuous. Gränges was seen as a troubled company, but when Electrolux bought it in 1980, Werthén had already been chairman of its board for three years and had overseen a marked upturn in its fortunes. Gränges became part of Electrolux in 1980, and by the late 1980s Gränges' aluminum products and car seat belts represented a major aspect of Electrolux's business, although other parts of Gränges were sold off.

Under the presidency of Anders Scharp, which began in 1981, Electrolux's program of acquisitions began to focus on the consolidation and expansion of existing lines. Takeovers became increasingly ambitious as Electrolux saw within its reach the chance to become one of the world leaders in household appliances. Major steps toward this goal were the acquisitions of Zanussi in Italy, White Consolidated in the United States (the third largest white goods company in that country), and the white goods and catering equipment divisions of the United Kingdom's Thorn EMI, in 1984, 1986, and 1987, respectively.

Through the years, Electrolux gained a reputation for buying only when the price was right and for turning around sick companies, even at the cost of heavy staff cuts and management shake-ups. As the Wall Street Journal pointed out in 1986 in a piece about the acquisition of White Consolidated, the group balance sheet looked unhealthy immediately after some of the larger acquisitions, showing an equity-asset ratio as low as 21 percent.

Electrolux bounced back confidently, making divestments as well as acquisitions. One of Werthén's earliest acts as president had been the 1968 sale of AB Electrolux's minority shareholding in the United States Electrolux Corporation to Consolidated Foods, which raised SKr 300 million, although the subsequent Eureka purchase had placed the company in the curious position of competing against its own brand name. Management continued this policy of judicious divestment following acquisitions, when it was considered that all or part of the new member did not fit in with the group's strategy. Facit, for instance, was sold to Ericsson in 1983, and shortly after the purchase of White Consolidated, its machine-tool division, White Machine Tools, was sold off.

Another method of raising cash was through the sale of assets, although Electrolux acquisitions were not primarily motivated by a desire to strip assets. In the case of Husqvarna, the purchase price of SKr 120 million was more than covered within six months by the sale of its land and other property. A third way of recovering the costs of acquisition was the use of a troubled company's accumulated losses wherever possible to reduce the group's tax liability. This was a major incentive in the acquisition of Gränges.

Not every company was delighted to hear Electrolux knocking on its door. Many a takeover was resisted by the target company, although Electrolux was also sometimes called in to rescue a troubled company (as happened with Zanussi) or asked to act as a white knight (notably for the U.S. household appliance company Tappan in 1979).

Geographic Expansion and Restructurings in the 1990s

The 1990s brought major changes to Electrolux, spearheaded by a new management team. Werthén resigned as chairman in early 1991, Scharp became chairman and CEO, and Leif Johansson was named president of the firm, taking over as CEO himself in 1994. During Werthén's long reign, Electrolux had grown tremendously through acquisitions but had failed to effectively consolidate the acquired operations into existing ones. The result was an unwieldy array of brands, each of which needing the support of separate production and marketing operations. Electrolux was further hurt in the early 1990s by an economic downturn in its core European and North American operations and by the maturing of the white goods sectors in those same markets, which intensified competition. All told, profits for Electrolux from 1990 through 1994 were much lower than the heights reached during the late 1980s. The new management team responded by seeking out new markets for its core products, by gradually divesting its noncore industrial products operations, and by streamlining its remaining business units.

Electrolux targeted Eastern Europe, Asia, South America, the Middle East, and southern Africa in its 1990s push for global growth. The company had already, in 1989, arranged for Sharp Corporation to distribute some of Electrolux's products in Japan. Subsequent moves in Asia included the setting up of joint ventures in China for the manufacture of compressors, vacuum cleaners, and water purifiers, and the acquisition of majority stakes in refrigerator and washing machine factories in India. In January 1996 another Chinese joint venture was established for the production of refrigerators and freezers for commercial users. The newly opened markets of Eastern Europe were first targeted with the 1991 purchase of the Hungarian white goods company Lehel. A 1995 joint venture with Poland's Myszkow FNE Swiatowit began making washing machines under the Zanussi brand. In Latin America, where Whirlpool was dominant, Electrolux acquired 99 percent of Refrigeraçao Paraná S.A. (Refripar) in 1996. Refripar (soon renamed Electrolux do Brazil) held the number two position among Brazilian white goods companies. Also in 1996, Electrolux purchased a 20 percent stake in Atlas Eléctrica S.A. of Costa Rica, the leading producer of refrigerators and stoves in Central America. By 1994, about 10 percent of Electrolux's sales came from outside the European Union and North America. This figure more than doubled by 1996 to 20.4 percent, with non-EU Europe accounting for 7 percent, Latin America for 6.4 percent, Asia for 5.1 percent, Oceania for 1 percent, and Africa for 0.9 percent.

While undergoing this global expansion, Electrolux also moved gradually to concentrate solely on three core sectors: household appliances, commercial appliances, and outdoor products. Profits in the company's industrial products sector were falling and Scharp and Johansson determined that these noncore operations should be jettisoned. The culmination of this process came in 1996 and 1997, with the divestment of the Constructor group, producers of materials-handling equipment; the sale of the Swedish electronics operations of Electrolux Electronics, and a sewing machines unit; and the spinoff of Gränges to the public. The final divestment came in August 1997 when Electrolux's goods protection operation, which sold tarpaulins and storage halls, was sold to MVI, a privately owned investment fund.

Electrolux greatly reduced its acquisitions activity in the European Union and North America in the 1990s, although there was one major addition. In 1992 the company bought a 10 percent stake in AEG Hausgeräte, the household appliance division of Germany's Daimler-Benz. This stake was increased to 20 percent in 1993 and the following year Electrolux purchased the remaining 80 percent for about US$437 million. The purchase brought the company another strong European brand, which fit well into a renewed brand strategy for Electrolux. The company sought to position the Electrolux brand as a global brand and Electrolux, Zanussi, and AEG as pan-European brands, while continuing to maintain strong local brands such as Faure in France and Tricity Bendix in the United Kingdom.

Along with the new brand strategy, Electrolux began in 1996 to reduce its fragmented operations and become more efficient. A pan-European logistics function was set up for white goods and floor-care products. In late 1996 the company's North American white goods operation, Frigidaire Company, was combined with the two North American outdoor products companies, Poulan/Weed Eater and American Yard Products, to form Frigidaire Home Products. Merging these operations made strategic sense since the trend in retailing was toward single retailers selling both indoor and outdoor appliances. Similar consolidations were planned for Electrolux's operations elsewhere in the world.

In April 1997 Johansson left Electrolux to become the chief executive at Volvo AB. Replacing him as Electrolux president and CEO was Michael Treschow, who had been president and CEO at Atlas Copco AB, a maker of industrial equipment and, like Electrolux, part of the Wallenberg dynasty. It was left to Treschow to announce, in June 1997, a major restructuring plan, which had already been agreed upon before he took over. Over a two-year period, Electrolux would lay off more than 11,000 of its workers (11 percent of its workforce) and close 23 plants and 50 warehouses (half of its global total), with the reductions coming mainly in Europe and North America. A charge of SKr 2.5 billion (US$323 million) was incurred as the result of the restructuring in the second quarter of 1997.

Under the leadership of Treschow, Electrolux further streamlined its operations in 1998, divesting its recycling business, its kitchen and bathroom cabinets interests, and various professional cleaning and heavy-duty laundry equipment units. The following year, the firm sold off its food and beverage vending machine businesses and its professional refrigeration equipment business. That year, Electrolux nixed a large portion of its direct sales force.

The company completed its restructuring efforts in 1999 and began to focus on maintaining its leadership position in the future. Treschow was confident that the firm's efforts would pay off, claiming in a 1999 Appliance Manufacturer article that the company was "ideally placed to meet the challenges of the new millennium." To back up that claim, the company began to develop new products that utilized cutting edge technology. In 1999, it teamed up with Ericsson to develop and market products for the "networked home." Managed under the joint venture, e2Home, these products would be connected via the Web to a variety of information and service providers. Another product line, the Live-In Kitchen, connected appliances to mobile phones, which among other features, allowed the owner to preheat their oven from their cell phone. As part of its foray into new technology, Electrolux also developed the Trilobite vacuum cleaner, a robotic product that used sensors to vacuum a room, and a Smart Fridge, a top-of-the-line refrigerator complete with built-in computer screen and Internet access.

Focusing on Brand Alignment in the New Millennium

By 2000, both sales and net income had increased steadily over the past three years. Sales had grown from SKr 113 billion to SKr 124.4 billion. Net income also had recovered, skyrocketing from SKr 352 million recorded in 1997, to SKr 4.4 billion secured in 2000. During that year, the company repurchased its rights to the Electrolux brand in North America, which it had sold in 1969 upon divesting its U.S. floor-care company. The purchase was part of its plan to align its brand names, especially in North America.

The company's operating environment became turbulent in 2001. Weakening demand and high costs related to upgrades at its refrigerator factories in North America forced the firm's operating income to fall by nearly 23 percent over the previous year. Despite these challenges, the company made two key acquisitions, including Email Ltd., Australia's largest household appliance manufacturer, and Italy-based Marazzini, a lawn mower manufacturer.

In April 2002, Hans Straberg took over as president and CEO as Treschow left the firm to head up Ericsson. Under new leadership, Electrolux shifted its focus from cost cutting to brand realignment. At the time, the company managed more than 50 different brands. The Economist reported in April 2002 that the company realized that "rationalizing the brands can be dangerous if done too quickly--so the rebranding will be more evolution than revolution. The Electrolux name will become the master brand, but the company will keep strong local brands, such as the Flymo lawnmower in Britain."

Facing strong competition and uncertain economic times, Straberg most definitely had his work cut out for him. Although the repositioning of the Electrolux brand name would no doubt face challenges, the company appeared to be well on its way to maintaining its leadership position in the appliance industry in the years to come.

Principal Subsidiaries: Electrolux Home Products Pty. Ltd. (Australia); Electrolux Hausgerate GmbH (Austria); Electrolux Home Products Corp. N.V. (Belgium); Electrolux do Brasil S.A. (99.9%); Electrolux Canada Corp.; Electrolux Home Appliances Co. Ltd. (China); Electrolux Holding A/S (Denmark); Oy Electrolux Ab (Finland); Electrolux France S.A.; Electrolux Deutschland GmbH (Germany); Electrolux Kelvinator Ltd. (India; 76%); Electrolux Zanussi S.p.A. (Italy); Electrolux de Mexico, S.A. de C.V.; Electrolux Associated Company B.V. (The Netherlands); Electrolux Norge AS (Norway); Electrolux Espana S.A. (Spain); Husqvarna AB; Electrolux Professional AB; Electrolux Holding AG (Switzerland); Electrolux UK Ltd.; Electrolux Home Products Inc. (U.S.A.); Electrolux North American Inc. (U.S.A.).

Principal Competitors: BSH Bosch und Siemens Hausgeräte GmbH; GE Consumer Products; Whirlpool Corporation.



Further Reading:

    "Brand Challenge; Electrolux," Economist (U.S.), April 6, 2002.
    Brown-Humes, Christopher, "Electrolux to Plug into Households in Opening Markets," Financial Times, April 27, 1995, p. 25.
    Burt, Tim, "Electrolux Set to Pull Out of Industrial Goods," Financial Times, October 30, 1996, p. 28.
    Calian, Sara, "Electrolux to Cut Force by 11%, Mainly in North America, Europe," Wall Street Journal, June 13, 1997, p. A15.
    Canedy, Dana, "Electrolux to Cut 12,000 Workers and Shut Plants," New York Times, June 13, 1997, p. D2.
    "Can 'Mike the Knife' Give Electrolux a Net-Age Edge?," Business Week, September 13, 2000.
    "Electrolux Expects to Be No. 1 Appliance Maker," Appliance Manufacturer, February 1994, p. 20.
    "Electrolux News," Appliance, December 1999, p. 18.
    "Electrolux News," Appliance, May 2002, p. 15.
    "Electrolux Plots a New Strategy," Housewares, January 1, 1990, p. 78.
    "Electrolux Sweeps into America," Business Week, September 23, 2002.
    Electrolux: Two Epochs That Shaped a Worldwide Group, Stockholm: Electrolux, 1989.
    Gordon, Bob, Early Electrical Appliances, Princes Risborough, United Kingdom: Shire Publications Ltd., 1984.
    Holding, Robert L., "Globalization: The Second Decade," Appliance Manufacturer, May 1999, p. 34.
    Jancsurak, Joe, "Big Plans for Europe's Big Three," Appliance Manufacturer, April 1995, pp. 26-30.
    Kapstein, Jonathan, and Zachary Schiller, "The Fast-Spinning Machine That Blew a Gasket," Business Week, September 10, 1990, pp. 50, 52.
    Lorenz, Christopher, "The Birth of a 'Transnational,'" Financial Times, June 19, 1989.
    McGrath, Neal, "New Broom Sweeps into Asia," Asian Business, March 1996, p. 22.
    McIvor, Greg, "Electrolux Comes Under the Scalpel," Financial Times, October 29, 1997, p. 19.
    Moss, Nicholas, and Hale Richards, "Mike the Knife Cuts Deep," European, June 19, 1997, p. 17.
    Racanelli, Vito, "Autumn Fall for Electrolux," Barron's, July 29, 2002.
    "The Real Head of the Household," Director, November 1996, p. 17.
    Reed, Stanley, "The Wallenbergs' New Blood," Business Week, October 20, 1997, pp. 98, 102.
    Sparke, Penny, Electrical Appliances: Twentieth-Century Design, New York: E.P. Dutton, 1987.
    "The Stars of Europe--Survivors," Business Week, June 11, 2001.
    "Sweden's Electrolux Plans for Expansion into Southeast Asia," Wall Street Journal, January 4, 1995, p. B7.
    Tully, Shawn, "Electrolux Wants a Clean Sweep," Fortune, August 18, 1986, p. 60.
    Zweig, Jason, "Cleaning Up," Forbes, December 11, 1989, p. 302.

Source: International Directory of Company Histories, Vol. 53. St. James Press, 2003.